It's not very difficult at all....17mm wrench, 17mm Socket, 12mm socket with driver, breaker bar, impact gun, I'd give it a 3 if your doing coilovers, a 4 if your changing springs alone. just remember to mark where your front camber bolts were. You'll have to get an alignment anyways but it does help a bit.
Coilovers aren't that bad, I put tein flexes on an s2000 in an afternoon and you have to unbolt alot of crap on that suspension to get them in there. Should not be that bad. You'll probably spend longer fine tuning ride height than installing them